The present invention relates generally to apparatus and methods for capturing particulate material within a blood vessel or other body lumen, and more particularly to apparatus and methods for capturing and/or removing particulate material, such as thrombus or other occlusive material, released or removed from a treatment site, e.g., an occlusion, within a blood vessel.
A number of endovascular procedures are presently performed on patients with atherosclerotic disease and the like to treat stenoses, occlusions, lesions, or other regions within the patient""s blood vessels, such as within the coronary, carotid or cerebral arteries. For example, an angioplasty procedure may be used to dilate a stenosis, or a thrombectomy or atherectomy may be performed to open severely occluded regions. A stent or other prosthesis may be implanted to retain patency of a vessel, either alone or in conjunction with these procedures.
One of the problems with these procedures, however, is that particulate, e.g., thrombus, atheroma, or other embolic or occlusive material may be released from the wall of the vessel during the procedure. If such particulate travel downstream, they may become lodged or otherwise harm the patient. For example, ischemic stroke may occur when such emboli are released in the carotid or cerebral arteries and travel to the patient""s brain.
To prevent or minimize damage from emboli, vascular filters have been suggested that are generally mounted on a device, such as a catheter, a guidewire, or a sheath. These devices may be introduced within a blood vessel downstream of a location being treated, and the filter on the device deployed across the vessel to capture embolic material released during a procedure, such as one of the procedures above. Upon completion of the procedure, the filter may be collapsed, trapping emboli therein, and then the device may be removed from the patient.
Alternatively, procedures have been suggested that involve deploying a balloon or other occlusive device downstream from a treatment site. The balloon may be expanded to prevent blood flow, thereby trapping any emboli released during the procedure. An aspirating catheter may be advanced into the vessel upstream of the balloon, and vacuum applied to remove the emboli before deflating and removing the balloon. Because this procedure completely blocks the vessel from fluid flow, the balloon may not be inflated for extended periods of time without depriving locations downstream of blood supply, which may be harmful to the patient.
Implantable filter devices have also been suggested that may be deployed, expanded and released within vessels, such as vena cava filters. These filter devices may not be recovered, or may it remain within the vessel for extended periods of time, where they may eventually become occluded with thrombus, clots, emboli and the like, which may harm the patient.
Accordingly, apparatus and methods for capturing and/or removing particulate material, such as thrombus or occlusive material, within a blood vessel would be considered useful.
The present invention is directed to apparatus and methods for capturing particulate material within a blood vessel or other body lumen, and more particularly to apparatus and methods for capturing and/or removing particulate material, such as thrombus or other occlusive material, released or removed from a treatment site, e.g., an occlusion, within a blood vessel.
In accordance with one aspect of the present invention, an apparatus is provided that includes a tubular member or jet housing including an inlet and an outlet. The tubular member has a cross-section substantially smaller than a cross-section of a body lumen such that the tubular member may be introduced into a body lumen generally parallel to a natural direction of fluid flow within the body lumen such that the outlet is oriented downstream of the inlet within the body lumen. A nozzle is disposed within the tubular member and oriented to inject fluid towards the outlet for generating a vacuum at the inlet.
A filter element is disposed on the inlet, the filter element including a plurality of openings having a predetermined maximum size for preventing particulate larger than the maximum size from entering the inlet of the tubular member. In one embodiment, the filter element may include a filter mesh covering the inlet, the plurality of openings including a plurality of pores in the filter mesh. In a second embodiment, the filter element may be a tubular body extending from the inlet, the tubular body including the plurality of openings in its wall.
In addition, the apparatus may include an aspirating element for removing particulate captured by the filter element. For example, the aspirating element may be a catheter that is advanceable over the tubular member, the catheter including a lumen for removing particulate captured by the filter element.
In accordance with another aspect of the present invention, a method is provided for capturing particulate within a body lumen of a patient. A tubular member may be positioned within a body lumen, the tubular member including an inlet and an outlet, the inlet being located upstream of the outlet within the body lumen. A jet of fluid may be injected from within the tubular member towards the outlet, the jet creating a vacuum at the inlet, the vacuum being sufficient to cause fluid downstream of the outlet to flow retrograde through the body lumen around at least a portion of the tubular member into the inlet. A filter element may be provided on the inlet, the filter element including a plurality of openings having a predetermined maximum size for preventing particulate larger than the maximum size from entering the inlet, thereby capturing the particulate at a location upstream of the outlet of the tubular member.
The captured particulate may be removed from the body lumen. For example, the particulate may be aspirated from the location upstream of the outlet, e.g., by advancing a distal end of a catheter into the body lumen to aspirate the particulate into the catheter.
The method may be performed along with one or more other interventional procedures at a location upstream from the tubular member, the procedure releasing material from a wall of the body lumen. For example, the procedure may include diagnostic and/or therapeutic interventions, such as thrombectomy, atherectomy, angioplasty, thrombolysis, endarterectomy, and/or stent delivery, such as coated stent delivery, drug eluting stent delivery, and the like.
In accordance with yet another aspect of the present invention, an apparatus is provided that includes a first elongate member including a distal portion having a size for introduction into a body lumen and defining a longitudinal axis. A tubular filter element is also provided having first and second ends adjacent first and second respective portions of the filter element. The first end is substantially fixed to the distal portion of the first elongate member, and the second end is movable axially with respect to the distal portion of the first elongate member towards the first end to evert the filter element. Preferably, the filter element is biased to assume a predetermined configuration programmed into a shape memory of the filter element material when the filter element is everted, the second portion being located substantially within the first portion in the predetermined configuration.
In a preferred embodiment, the apparatus also includes a second elongate member including a distal portion to which the second end of the filter element is fixed. The second elongate member is slidable along the first elongate member for moving the first and second ends of the filter element towards one another to cause the filter element to evert. Preferably, the second elongate member includes a lumen through which the first elongate member is slidably received.
Similar to the previous embodiment, the apparatus may also include an aspirating element having an inlet that may be disposed within an interior of the filter element in the predetermined configuration.
In one embodiment, the filter element may define a space between the first and second portions in the predetermined configuration, and the first portion may include pores therein that are substantially smaller than pores in the second portion. The filter element may include one or more struts extending from the second portion of the filter element to a distal end of a second elongate member slidably disposed on the first elongate member.
Preferably, the filter element is biased to assume an expanded tubular configuration when the second portion of the filter element is removed from within the first portion.
To manufacture a filter element in accordance with the present invention, an elongate tubular mesh or braid may be provided having first and second ends, and first and second portions adjacent the first and second ends, respectively. The tubular mesh may be shaped into an everted configuration in which the second portion is disposed concentrically within the first portion. The tubular mesh may then be heated to a predetermined temperature to program the everted configuration into a shape memory of the tubular mesh. After heating, the second portion may be removed from within the first portion to dispose the tubular mesh in a generally tubular configuration, the tubular mesh maintaining the tubular configuration in a relaxed state.
First and second elongate members, e.g., coaxial guidewires, may be attached to the first and second ends of the tubular mesh, respectively. The first and second elongate members may be movable axially with respect to one another to move the first and second ends towards and away from one another.
The filter element may be used to capture particulate within a body lumen, e.g., a blood vessel, at a location downstream of a treatment site. The distal portion of the elongate member may be advanced to a location within a body lumen downstream of a treatment site, the tubular filter element being disposed in a radially compressed configuration. The first and second ends of the filter element may be directed towards one another, whereupon the filter element may automatically evert such that the second portion is located substantially within the first portion, and an intermediate portion between the first and second portions expands to engage a wall of the body lumen.
Particulate passing along the body lumen may be captured within the everted filter element, and the particulate captured within the filter element may be aspirated. The first and second ends of the filter element may then be moved away from one another to remove the second portion from within the first portion. The filter element may be collapsed radially inward, and the filter element may be removed from the body lumen.
Other objects and features of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings.